An underwater communication device for a conversation in water is conventionally disclosed (refer to, for example, Patent Literature 1). Some of such underwater communication devices have a structure covering the mouth and the like of a diver by using a mask such as a full face mask or a half mask so that the diver can freely move the nose, the mouth, and the lips. By using an underwater communication device of this kind, a diver can utter voice with clear pronunciation like he is on land.
However, a mask covering the mouth and the like has a structure which cannot be easily detached and, if it is not properly used, suffocation due to air shortage or vomiting may be caused. Consequently, an actual situation is that the underwater communication device of this kind is used only by a diver who has to talk in water in the course of business such as a diver for military purpose or fire service or an underwater reporter and is not used by a leisure diver.